Jominy test, Mechanical Engineering

Jominy Test:

Additionally convenient laboratory test for harden-ability is Jominy test. A standard test piece of steel as illustrated in figure of The Jominy Test of Harden-ability is austenitized in usual manner. The lower end of the test piece is then quenched via a standard jet of water, resulting in a varying cooling rate.

271_Jominy Test.png

Figure: The Jominy Test of Hardenability

The cooling rate at the jet end is about 300oC/sec whilst such at the other end is about 3oC/sec. it varying rate of cooling produces a broad range of hardness along the length of Jominy test piece. A flat portion is ground beside the length and hardness measured at different points. The plot of hardness along the length offers Jominy index of harden-ability.

The best utilization of the Jominy curve is made via drawing a horizontal line consequent to hardness of the semi-martensite zone. The semi-martensite zone hardness is explained in Table no.11. The point where such line requires the Jominy curve calculates the distance from the quenched end that can be inserted in figure of calculating the Diameter of Fully Hardened Articles as per to the Distance from the Quenched End  to find out the diameter for a particular steel that will be fully hardened in water or oil.

1959_Jominy Test1.png

Figure: Harden-ability Curves Plotted from End Quench Test Data

a)      For Shallow; and

b)      For Deep Hardening Steel

Figure: finding the Diameter of Fully Hardened Articles as per to the Distance from the Quenched End

Table no.1: Relationship between the Hardness of the Semi-Martensite Zone and the Carbon Content

Carbon-content %

Hardness of the Semi-martensite (Rc)

Carbon Steel

Alloy Steel

0.08 - 0.17

-

25

0.13 - 0.22

25

30

0.23 - 0.27

30

35

0.28 - 0.32

35

40

0.33 - 0.42

40

45

0.43 - 0.52

44

50

0.53 - 0.62

50

55

Posted Date: 2/26/2013 5:58:05 AM | Location : United States







Related Discussions:- Jominy test, Assignment Help, Ask Question on Jominy test, Get Answer, Expert's Help, Jominy test Discussions

Write discussion on Jominy test
Your posts are moderated
Related Questions
Q. Explain Machining allowance? Machining allowance or finish allowance indicates how much larger the rough casting should be over the finished casting to allow sufficient mat

Permanent Way: Definition In railway engineering, the permanent way refers to the earthen formation and the track structure over it. Gauge The separation

what is the affect of ambient temperature on the performance of GAS turbine

Q. Why we need paving in design of a plant? Concrete paving should be provided under any equipment where flammable or hazardous liquids may be spilled during routine operation

its definition, principle, explanation, application, and a diagram

Explain the Effect of Cutting Speed Increase in cutting speed improves the surface finish due to the continuous reduction in built up edge. The curve a represents the machining

WORKSHOP DISCIPLINES Following discipline tips should be made a part of life to become a good technician. These will certainly help in creating safe, friendly and clean enviro

when the governor is connected to a engine its sensitiveness formula change,why?

i am try to make a vacuum tube oscillator for a larger project but i need help where to find the supplies for it where can i find them

strain energy = m2l/2Ei